So the frequent question is asked, 'How do I access NTFS through OpenBSD?'. But I want to know something slightly different. I need to use XP for the next two years for certain reasons, like I need to use Delphi, open Office '07 documents, use common software, etc - It just ain't happening on OpenBSD, even though I prefer it.

Before I wipe OpenBSD, I will need to copy a large amount of data from my BSD partition to a NTFS equivalent. Or, I could just use software that allows me to access BSD partitions through XP, but I don't think such software exists. So, should I make a NTFS partition now, copy the data across, then install XP on the other NTFS partition, or should I make a new NTFS partition, install XP on it, then copy the BSD partition data to a NTFS one through XP?

I'm assuming that the first method will require Samba to get to the NTFS partition?

Assumption: you have a single computing system available, and are currently multibooting.

Samba, or any other network-based solution for file transfer requires at least two systems.

The easiest way to transfer data within a multiboot system is to use a second disk drive or to use an external storage device. And the easiest filesystem to use, because it is supported by both XP and OpenBSD, is FAT32. You won't have any permission or ownership information, but you can copy files up to 4GB in size.

(NTFS support on OpenBSD is read-only and requires a custom kernel.)

If you have no external storage, and only a single hard drive shared by both OSes, and no external platform to transfer files from and to.... you could still craft a networked solution while running OpenBSD in a virtual machine as a guest of XP. The specifics of such a solution would depend on the virtual machine software you choose.

Apologies, I should have really elaborated on my situation a little more.

I'm running a single machine, with one OS - OpenBSD. I have two partitions, one for /, since I don't use the home folder for any really important data, I didn't bother separating it. It is a UFS partition. The other partition (Which is also UFS filesystem) is under /mnt/Files, and contains all the data I wish to keep separate from the system, like music, documents, home/etc backups, setup files, etc.

I have a external drive which runs NTFS. It's the only drive I can do it with, due to the size, and it's NTFS over FAT32 because it's actually a SATA drive in a caddy, which 'turns' it into a external USB drive. So, to read/write to the drive, I will need to have NTFS support. I wish to copy all the data I have on the UFS partition onto the NTFS drive, format my machine's HDD accordingly, then put the data back onto a dedicated NTFS partition. Converting the drive from one filesystem to another with the data might work, but sounds a little risky (If it can even be done from UFS to NTFS).

The suggestion of a VM is really good - I am thinking that I could use VMware with OpenBSD in XP to access the partition. And, ofc, I will look at the software posted.

Apologies, I should have really elaborated on my situation a little more.

The reason the solutions presented are elaborate are due to what jggimi stated -- NTFS support in OpenBSD is deemed experimental. Reading from NTFS partitions is reasonably safe, but writing may have disastrous results. If you are wanting to read & write, then using the lowest common denominator supported by both OS'es, FAT32, is a reasonable solution. Otherwise, you will need to go through the contortions of a VM.

Since you are only running OpenBSD, and NTFS under OpenBSD can, if you enable it, only move data from NTFS and not to it.... NTFS is not an appropriate mid-point storage medium.

To install XP on your system requires free, unallocated space at the MBR level. If you had unallocated space you could give to a new MBR partition, you could set up XP to multiboot. If you do not have that space, you will have to reconfigure OpenBSD, or replace it.

There is no difference in how I/O is conducted with a USB mass storage device, be it IDE/PATA, SATA, or Flash memory. You *could* format your external USB device as FAT32 -- up to 2TB is possible with default cluster sizes, up to 8TB is possible with 32KB clusters.

All it takes is fdisk(8), disklabel(8), and newfs_msdos(8).

There are three limitations to using FAT32: 1) there is no concept of file ownership. 2) there is no concept of file access control, other than a read/only bit. 3) The maximum individual file size is 4GB. The latter should not be a show stopper, as there are ways to break up larger files if you have them.

You could back up all of your OpenBSD files-of-interest to FAT32, replace OpenBSD with XP on the hard drive, then restore those files to your system's hard drive. After that, you could restructure the external drive's MBR table and format as desired from XP.

If it were me, and this single-system with one internal and one external disk drive were what I had .... and OpenBSD -> XP was my objective, this is what I would do.

For various reasons, the external caddy drive can't be screwed with, only the computer's drive.

However, I think I may have another spare IDE drive and a IDE caddy, so I could format that as FAT32, and use it for UNIX-Windows compatibility stuff.

I'm, thinking of doing the following - shrink an existing UFS partition, put a FAT32 partition in the free space, copy the files across, delete all the other partitions, install XP on a small partition, extend the FAT32 partition as needed, then convert it to NTFS, since the FAT32-to-NTFS converter that comes with XP has always worked for me and has never lost data.

A little complicated, I know. Using NTFS has always been more successful for me over FAT systems, so I think I will use it, despite its OpenBSD incompatibility. After all, it will be about two years.

Thanks for telling me. I think I have it sorted. I will just access it through a VM. If that fails, I recover it from my out-of-date NTFS backup, which I have rare access to, and won't cover everything, which will be a pain, but I will have to do it.

I'd try to stay away from anything too convoluted. Any time you add complexity, you add opportunities for data loss. Virtual machines can be difficult or cumbersome; for example, do you need to restructure OpenBSD before you can install XP on the same disk drive?

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The entire requirement, as I understand it, is to:

Back up some files that currently reside on OpenBSD.
Restore them on a soon-to-be-installed WXP system.

If the external NTFS drive cannot be freely reformmated and then later returned to NTFS, then that drive cannot be used as a transition tool.

If you are able to obtain a second drive, as you surmise might be possible, then I would format that drive as FAT32, back up the files-of-interest, and then install XP where OpenBSD used to be.

I would stay far away from growing / shrinking / converting. Of anything. At least until the data has been safely restored to the original drive in NTFS format. The risk of confusion, finger fumble, or other mistake are higher than that of a software bug, and the chance of a software bug with filesystem manipulation is greater than zero.

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There are other alternatives, too, that don't involve FAT32. Backing up to optical discs, for example. And for that, both OpenBSD and XP understand ISO 9660 and UDF, though they use different extensions -- Rock Ridge and Joliet, respectively.